Originally Posted by
Loren Pechtel
You'll almost certainly need to reactivate Windows after bringing it into the VM--it's going to see truly massive hardware changes as *EVERYTHING* will have been replaced.
I wouldn't run a VM from an external drive--it's going to be *SLOW*. Note, also, that the disk images for VM's are just as big as the disks they replace although they can be demand-allocated (this causes a performance penalty).
I've never tried to do anything other than use an image built within the VM so I can't comment on how an import goes.
My experience is somewhat different, after having built close to 100 VM images for various labs, seminars, operations, etc...
Second disk has always improved performance, even if it's just a USB 2.0 case running a 7200rpm 2.5" IDE disk. VMs are heavy on storage IO hitting both the VM's own disk files and the host bits. Storage isolation is a necessity for performance. Most laptops come with cheapo 5200rpm IDE or SATA drives so you're getting barely 70-80IOPS sustained. That burns up in a heartbeat when you have a VM running on the same disk as your host.
The total size of my VM virtual disks (or disk) is smaller than bare metal installations for Windows because we always turn off recovery for any/all VM drives. It's a waste of time for recovery purposes, wastes disk space and can affect performance when Windows pages (and it will regardless of how much RAM you have).
Demand allocated or dynamic disks are an absolute no-no if you care about performance. Used a fixed size disk and pre-allocate right from the start.